"Stranded on Earth for more than half a century, an alien assassin observes humanity’s capacity both for compassion and for destruction," is how co-writer Chris Roberson describes the five-part storyline launching next year.

Heat Visionhad the first glimpse at the new Mike Mignola project The Visitor: How and Why He Stayed on Monday, and now more details about the series have been announced — including the fact that it'll address one of the stranger mysteries of the Hellboy mythology.

The five-issue series — which will be written by Mignola and Chris Roberson, with art by Paul Grist — will follow up on something from the very first Hellboy miniseries, published back in 1994.

"In Hellboy: Seed of Destruction, readers were given a brief glimpse of a crew of strange looking aliens monitoring the supernatural doings on Earth from way out in space," Roberson — who's also working with Mignola on the ongoing Hellboy and the BPRD comic book series — said in a statement. "We later learned that one of those aliens had been sent to Earth to kill [Hellboy] in 1944, but chose to spare him at the last moment. In The Visitor, we explore who those aliens are, why that assassin was sent to kill Hellboy and just what he was doing in all of the years in between."

The series will follow the evolution of the Hellboy universe through the eyes of the alien assassin, Roberson explained. "Stranded on Earth for more than half a century, an alien assassin observes humanity’s capacity both for compassion and for destruction. We see history unfold through his eyes, just as the experience of living among humans changes who he is."

The Visitor: How and Why He Stayed launches with a prologue in the January-shipping Hellboy Winter Special 2017, before the debut of the five-issue series proper Feb. 22.